1. Field of the Invention
The present invention relates to fuel tank for an automobile or the like as well as manufacturing method thereof. The fuel tank contains therein functional components such as a valve, a pump and the like. Particularly, the present invention relates to a fuel tank formed by blow molding, in which the function components are integrally disposed in the fuel tank.
2. Related Art
Functional components such as a fill-up regulating valve, a fuel pump, etc. are disposed in a fuel tank for an automobile. These functional components are indispensable for smoothly feeding fuel to an engine or the like.
The functional components are commonly disposed via a flange etc. from outside the fuel tank. When the functional components are disposed via the flange, however, a seal member such as an O-ring or the like need be separately attached in order to secure the airtightness or liquidtightness in the periphery of the disposition portion.
To solve the above drawback, a resin fuel tank in which the functional components are disposed on the inner wall side of the fuel tank without using any flange is presented.
Japanese Unexamined Patent Publication JP 01-301227 has conventionally been known as such a kind of fuel tank. The fuel tank has substantially the shape of a rectangular parallelepiped, which is formed by upper and lower walls of substantially rectangular shape and a side wall provided therebetween and surrounding the upper and lower walls. A synthetic resin plate is fixedly held in the fuel tank so as to be clamped by the inner peripheral surface of the side wall. An outer wall constituting the upper, lower, and side walls is formed by blow molding. Functional components such as a cutoff valve, a pump unit, etc. are attached to the synthetic resin plate.
FIG. 19 shows a sectional view of such a fuel tank 208. A tank body 207 has a hollow rectangular parallelepiped shape. Also, the tank body 207 is made of resin by blow molding. A plate-like module 203 is configured by a resin base body 209 and the functional components 200 disposed on the base body 209. The module 203 is bridgingly disposed between the mutually opposite inner wall side surfaces of the tank body 207.
Conventionally, the functional components 200 are integrally disposed in the plate-like module 203, and the plate-like module 203 is bridgingly disposed in the tank body 207. Thus, the functional components are disposed on the inner wall side of the fuel tank.
In the fuel tank, after the functional components are pre-assembled to the synthetic resin plate, the tank wall is formed by blow molding. Hence, a tank opening can be made small, thus enabling improvement in assembly operation properties through the tank opening.
In the conventional fuel tank, it has been required to increase mechanical strength of the tank wall and enhance safety at the time of collision to protect the functional components. Also, it has been required to decrease a change in tank capacity due to tank internal pressure and improve accuracy of a system for sensing a change in tank internal pressure and flow rate.
However, in the above conventional fuel tank, vertical rigidity of the fuel tank cannot be reinforced. That is, according to the above conventional fuel tank 208, the plate-like module 203 is disposed so as to be bridged between the mutually opposite inner wall side surfaces of the tank body 207. Consequently, although the horizontal rigidity of the fuel tank 208 can be reinforced, the vertical rigidity thereof cannot be reinforced. Since the plate-like module 203 is suspended in air in the tank body 207, the plate-like module 203 flexes under its own dead weight, and there is even a possibility that the vertical rigidity rather decreases.